Improvement in weighing-scales



F. M. STRONG 82: T ROSS.

PLATFORM SCALE.

No. 24,161. Patented May 24, 1859.

. by preventing the knife-edges abraded or injured.

UNITED STATES PATENT OFFICE.

FRANCIS M. STRONG AND THOMAS ROSS, OF BRANDON, VERMONT.

'uvl PROVEMENT N WEIG HlNG-SCALES.

Specification forming part of Letters Patent No. 24,161, dated May 24, 1859.

To all whom it may concern.-

vlugs, making part of this specification, in

which- Figure 1 is a plan showing the levers and,

the auxiliary intermediate frame on which'th'e platform rests; Fig. 2, a front elevation showing the levers, intermediate frame, and platform, also giving a sectional View of the manner of constructing the intermediate frame and apylying it and showing the manner of connecting the levers'to the beam; Fig. 3, an enlarged section showing more clearly the construction of the intermediate frame and shafts; Fig. A, an enlargedplan of 1 portions of shaft A and arm B, showing the manner of attaching and securing them together; Fig. 5, an elevation of .the same; Fig. 6, a horizontal section of the same; and Fig. 7, a View of the poise and a portion of the beam, showing the manner of graduating them.

The shafts A A, Fig. 1, have knife-edges inserted at their centers (shown at P, Fig. 3) in heads formed to receive them at or near each extremity. These knife-edges are the fulcrum of the levers A B A B and rest upon a bearing secured to the frame or foundation. Inwardly from these knife-edges, parallel to and all equidistant therefrom, are other knifeedges, on which rests what We .term. the intermediate frame 0, which supports the platform D. Concaves are formed at each corner of the intermediate frame to receive balls or spheres h, on which the platform rests, the under face of the said platform being in like manner formed with concave recesses to rest on .the balls, as shown in'Figs. 2 and 3. This.

manner of connection allows the platform to yield to any lateral movement without cornmunicatin g it to the intermediate frame, therefrom being The bearing-blocks Figs. 2 and 3, of the intermediate frame are not rigidly secured thereto, but areinserted in sockets, where they have room to rock on ribs projecting from their upper sides, so that they may adjust themselves to the knife-edges on which they rest, and they have at the same time an endplay in the direction 0f the length of the frame 0, so that they may adjust themselves to limited inequalities in the distance of the levers apart or variations of the length of the frame itself. These blocks are secured from dropping out of the sockets by staples c, Fig. 3. The intermediate frame 0 has also another peculiarity. It is made in two similar parts, each part forming one side and one end of the quadrangle, the two being joined at diagonally-opposite corners by links or other equivalent device, as shown in sectionin Fig. 2. -This allows it to yield to the transverse movement of theknife-edges on which it rests,

such transverse movement being caused by the oscillation of the levers'in arcs of circles in the operation of weighing. The advantage ofthis will be more obvious in those scales called drop-lever scales, as in them the transverse movement is considerable, and not only has a tendency to abrade the knife-edges,

but to otherwise impair the accuracy of the machine by cramping the free action of the levers. This frame 0 we sometimes construct of one piece; but this-may be dispensed with when the levers themselves are hung in loops or links, as in such case it is not so essential that it should yield to the transverse inbvement of the knife-edges, as the levers themselves can then conform to the frame, although it is preferable to join it by links, as above described.

The arms B B have their extremities n n placed one. above the other, and by thus placing them we attain a truly perpendicular connection of both with the beam, the upper one acting through the direct rod k, and thelower one acting upon the cross-bar at the lower end of the sling-rod g, which passes throughted to the beam from the two in oppositely inclined directions, and they would only to a certain extent counteract each othera defect which becomes obvious when the body that is being weighed is moved from the center to either end of the platform. The beam F, Figs. 2 and 7, is graduated to the larger divisions, these being subdivided by the scale upon the sliding poise f, graduated on the principle of the vernier.

The manner in which we clutch and secure the arms B B to the shafts A A is shown in Figs. 4, 5, and 6. The flange of the shaft A has a projection a, Figs. 4 and 5, against which a part of the arm B, projecting from the face of the flange forming the head, abuts. This last flange has a circular or annular tenon on. its face, which enters a corresponding rabbet in the flange of the shaft A. The whole is secured-by the single bolt 1), shaft A being cast to receive the nut c.

The operation is as follows: The weight placed upon the platform acts through the balls or spheres and intermediate frame 0 upon the knife-edges of the shafts A A, tending to turn them, and consequently to depress the ends of the arms B .3, and they actuate the beam where the weight is indicated. by the poise and weights in the usual manner; and although we have above described. but one mode of application of our said invention we do not wish to be understood as limiting our claim of invention to such mode, as other v 1. The employment of an auxiliary frame substantially such as described, in combination with and interposed between the platform and levers, substantially as described, and for the purpose specified.

2. Constructing such intermediate frame in two parts connected by movable joints at the angles, substantially as and for the purpose specified.

3. The manner of constructing and inserting the bearing-blocks that rest on the knifeedges, substantially as and for the purpose specified.

4:. Bringing the ends of the arms of the levers immediately one above the other, in combination with the mode of connecting the two with the beam by single and double connecting-rods, substantially as described, and for the purpose set forth.

FRANCIS M. STRONG. THOMAS ROSS. WVitnesses:

JOHN F. ESTABROOK, ROBT. Forums. 

